Standard library · The command line

cli/log

Imported as import "cli/log" as log, its names are then log.…. Every signature below is the one the checker infers.

Types

Log

• Log(name: Str, level: Int, to: Int)

Functions

fn debug_level() -> Int

log.level_name(log.debug_level())   # => DEBUG

fn info_level() -> Int

log.level_name(log.info_level())   # => INFO

fn warn_level() -> Int

log.level_name(log.warn_level())   # => WARN

fn error_level() -> Int

log.level_name(log.error_level())   # => ERROR

fn new(name: Str) -> Log

l = log.new("db")
l.name                             # => db
log.says(l, log.info_level())      # => true
log.says(l, log.debug_level())     # => false

fn from_env(name: Str) -> Log

The level from the RILL_LOG variable — debug, info, warn, error, or off — and info when it is unset or says something else.

import "cli/env" as env
env.set("RILL_LOG", "warn")
log.says(log.from_env("x"), log.info_level())   # => false
env.set("RILL_LOG", "nonsense")
log.says(log.from_env("x"), log.info_level())   # => true
env.unset("RILL_LOG")

fn level_named(word: Str) -> Int

log.level_named("warn") == log.warn_level()   # => true
log.level_named("loud") == log.info_level()   # => true

fn level_name(level: Int) -> Str

log.level_name(log.warn_level())   # => WARN

fn at(l: Log, level: Int) -> Log

l = log.at(log.new("x"), log.error_level())
log.says(l, log.warn_level())    # => false
log.says(l, log.error_level())   # => true

fn quiet(l: Log) -> Log

log.says(log.quiet(log.new("x")), log.warn_level())   # => false

fn named(l: Log, name: Str) -> Log

log.named(log.new("app"), "db").name   # => db

fn to_stdout(l: Log) -> Log

Writes to standard output instead — for a log that is the program's output, as a server's access log is.

l = log.to_stdout(log.new("access"))
l.to                          # => 1

fn debug(l: Log, msg: Str) -> Unit

l = log.at(log.new("x"), log.debug_level())
log.debug(l, "a detail")     # written, since the level allows it

fn info(l: Log, msg: Str) -> Unit

log.info(log.new("x"), "started")

fn warn(l: Log, msg: Str) -> Unit

log.warn(log.new("x"), "slow request")

fn error(l: Log, msg: Str) -> Unit

log.error(log.new("x"), "cannot open the file")

fn says(l: Log, level: Int) -> Bool

log.says(log.new("x"), log.error_level())   # => true

fn line(l: Log, level: Int, msg: Str, when: Str) -> Str

The line as it is written: time, level padded to five, name, message.

log.line(log.new("http"), log.info_level(), "up", "2026-09-15T21:04:05Z")   # => 2026-09-15T21:04:05Z  INFO   http  up

Tests

• test_levels
• test_the_line
• test_it_writes